ballplayer vs jock

ballplayer and jock both are nouns.

Word	Noun	Adjective	Verb	Adverb
ballplayer	Yes	No	No	No
jock	Yes	No	No	No

As nouns, jock is a hypernym of ballplayer; that is, jock is a word with a broader meaning than ballplayer:

Other hypernyms of ballplayer include athlete, participant, player.

ballplayer (noun)	jock (noun)
an athlete who plays baseball	a support for the genitals worn by men engaging in strenuous exercise
	a person trained to compete in sports